Efforts to increase daily physical activity have been targeted to physical education (PE) classes, as 97% of elementary school students take PE. However, it has been suggested that children only receive approximately 3 minutes of vigorous exercise during PE. Significance: This study determined how much time 4th grade students are actually spending in moderate-to-vigorous physical activity (MVPA) during a 30 minute PE class. Design: 48 fourth grade students (girls n= 30, age= 9.56 ± 0.39 years; BMI = 18.98 ± 3.60 kg•m-2; males n= 18, age= 9.69 ± 0.40 years; BMI = 18.57± 2.97 kg•m-2) from 3 elementary schools wore an MTI Actigraph accelerometer for 4 consecutive days. Time spent in MVPA was evaluated using activity thresholds established by Trost et al., (2001). Results: On average, children obtained 9.6 ± 6.9 minutes of MVPA during a 30 minute PE class and although not significant, boys obtained 25% more MVPA during PE compared to girls. Total daily physical activity was greater on PE days (135.61 ± 33.69 min) compared to non-PE days (123.84 ± 37.78 min) (p<0.05). This significant difference held true for girls (PE day = 131.46 ± 24.9 min; non-PE day = 114.92 ± 31.7 min, p<0.05), but not boys (p>0.05). Results suggest PE does increase daily MVPA, although modestly. Promotions to increase time spent in PE and frequency of PE may significantly increase total daily MVPA, especially for young girls. This study was funded, in part, by the American Heart Association. Keyword(s): active participation, measurement/evaluation, physical education PK-12